Safety webbing



United States Patent [72] Inventor JohnJ. Lowe South Hill, Va.

{21] Appl.No. 859,520

[22] Filed July 24,1969

Continuation of Ser. No. 682,743, Nov. 14, 1967, abandoned.

[45] Patented Dec. 29, 1970 [73] Assignee Burlington Industries, Inc.

Greensboro, N.C. a corporation of Delaware [54] SAFETY WEBBING 1 Claim,1 Drawing Fig.

[52] US. Cl. 297/385, 139/383, 139/420 51 Int. Cl A47c 3 00 [50] Fieldof Search 24/77; 297/385; 139/383, 384, 420, 426; 57/139, 140

[56] References Cited UNITED STATES PATENTS 2,309,564 III 943 Andersonet al 57/139 2,324,583 7/1943 Jackson. 57/139 3,196,509 7/1965 Frew24/77 3,322,163 5/1967 Hughes 139/383 Primary Examiner-Henry S. JaudonAttorney-C-ushman, Darby and Cushman ABSTRACT: Woven safety webbing foruse in automobile seat belts or the like characterized by increasedabrasion resistance. The webbing comprises, as the warp yarn, plied yarnmade up of two or more ends of singles yarn, the ply twist being in thesame direction as the twist in the singles before plying.

PATENIEUouzzsxsm 3,550,956

INVENTOR JA A JL0W5 ATTORNEYS,

, SAFETY WEBBING g This is a continuation of application Ser. No.682,743, Nov; 14, 1967 now abandoned.

The present invention is concerned with the provision of woven safetywebbing which demonstrates highly improved surface abrasion resistance.The woven webbing of the invention is particularly useful for automotivesafety restraint systems although other uses where surface abrasionresistance in webbing is important are also contemplated.

Safety webbing presently used for seat belts has relatively lowresistance to surface abrasion. For instance, in the adjustablebuckle-type of safety restraint system, abrasion normally occurs afterthe user snaps the belt buckle shut and then either tightens or loosensthe belt through the adjustable fea-' ture of the buckle. After about200 such cycles, the cumulative abrasion effect results in a thickeningof the webbing, making it increasingly more difficult to pull thewebbing through the buckle. In one particular type of buckleconstruction now in substantial use, the webbing must. be pulled over abuckle bar and then through a slot in the back of the buckle proper, andthis causes substantial abrasion, the webbing being abraded on one sideas it is drawn over the buckle bar and then on the other side as itpasses over the edge of the slot in the back of the buckle.

The principal object of the present invention is to provide aconvenientand effective solution to the problem of abrasion inautomotive or like safety webbing.- Other objects will also be apparentfrom the following detailed description of the invention.

Broadly stated, the present invention is based on the finding that awebbing of remarkably higher surface abrasion resistance is obtained ifthe webbing is woven with a plied yarn made up of two or more ends ofsingles yarn, the ply twist being in the same direction as the twist inthe singles before plying. Highly useful webbings of increased surfaceabrasion resistance may be made according to the invention, using a plyyarn of the above type as the warp yarn with conventional safety webbingyarn in the filling. However, if desired, both the filling and warp maybe plied yarns ofthe type indicated.

Use of a plied yarn having a ply twist in the same direction as thetwist in the singles before plying (referred to herein for convenienceas a twist-on-twist plied yarn) represents a marked departure fromconventional thinking in the art and the improved abrasion resistancethus obtained is very surprising. In conventional practice, the yarnused for automotive (or other vehicles) safety webbing is a plied yarn(e.g. 2 plied ends of 840 denier nylon yarn) but the ply twist isopposed to any twist in the preplied ends. Thus, for example, thesingles as recieved from the yarn manufacturer has a twist of aboutonehalf turn in the Z direction and they are then plied together for useby twisting 2% turns in the opposite direction (i.e. with S twist). Thisis consistent with usual practice in the art in that the use of a plytwist which is opposed to the singles twist will result in a morebalanced yarn condition with any tendency for the singles to untwist inone direction being at least partially offset by the tendency for theplied yarn to untwist in the opposite direction. 1

The amount of ply and preply twist in the yarns employed herein,according to the present invention, may be widely 'varied although itappears that the degree of abrasion resistance in the webbing is verymeasurably increased as the number of ply turns are increased. Usually,the preply twist in the singles will be in the range of one-fourth tothree turns per inch in either the S or Z direction although amounts ofsingles twist outside this range may also be used. The ply twist mayalso ver varied but usually will fall in the range of 2--10 turns perinch in the same direction as the singles twist. Ply twists outside theindicatedrange may be used depending on the denier of the yarn and otherfactors although in the case of the plied yarn as well as the prepliedsingles, it is generally preferred for ease of handling to stay belowthe point where the yarn becomes too lively.

Two or more ends of yarn (for example three or four) may be pliedtogether for present purposes. Typically, two ends of 840 denier orother heavy denier nylon yarn plied together as described are used asthe warp and the same or different yarn, e.g. singles 840 denier nylonor conventional two-ply, 840 nylon yarn, may used as the filling. i I

Apart from the use of a plied yarn of the type indicated i.e. ply twistin the same direction as singles twist) as the warp and, optionally, asthe filling, the safety webbings of the invention may be of conventionalconstruction. Thus, the number of warp and filling ends may be widelyvaried although usually the warp and filling ends 'will run about220-300 per webbing (based on a normal 1 15/16 inch width webbing) and14-20 per inch, respectively. Typically, the webbing is 1 15/ 16 incheswide as indicated although this may be varied if desired. Theconstruction employed is preferably a multipanel twill weave but othersafety webbing weaves may also be used. Usually, the yarn prior toplying (ie in the singles state) is 840 denier nylon although othersizes and types of yarn, or com binations thereof, may be used. Onerepresentative construction is a 2 by 2 four-way twill weave comprising,as the warp, 256 ends of two-ply 840 denier nylon,the singles in eachendhaving one-half turn Z producer twist and the plied ends having 3% turnsply twist also in the Z direction. The filling yarn (typically 15 picksper inch) may be, for example, a two-ply 840 denier nylon yarn (producertwist one-half turn 2 and ply twist 2% turns S). The nylon may be anyconventional type, e.g. nylon 6 or 66.

Another example of a safety webbing according to the invention is a 2 by2 three-way twill woven with 264 ends of twoply 840 denier nylon as thewarp, the ply twist (6 turns) being in the same direction Z as thepreply producers twist one-half turn) in the 840 denier nylon. Thislatter construction may include 15 picks per inch of two-ply 840 denieror other heavy denier nylon in the filling, the ply twist (2% turns)being opposed S to the twist in the singles. Other safety webbingconstructions are also contemplated as will be apparent. For instance,some or all of the nylon warp or filling ends referred to in the abovedescribed constructions; may be replaced by polyester or other yarns.For purposes of identification or otherwise, the webbing may include asmall number of warp ends, e.g. two or more, in singles form a pliedwith a twist different from the ply twist in the main body of warp ends.

The unique advantages of the present safety webbing are shown by thefollowing test results comparing conventional automotive safety webbingswith webbings of the present invention. The test employed involvedpulling the webbings through a conventional safety belt buckle for 6inches in one direction and then 6 inches in the other direction tocomplete one full cycle. The only difference between the webbingscompared was that in the webbings representative of the invention, thewarp yarn was a twist-on-twist" plied yarn whereas, in the constructionrepresentative of conventional practice, the warp yarn was a plied yarnwith the ply twist opposed to the preply twist. Each webbing was wovenof 264 ends and 15 picks per inch. Two such webbings (each 1 15/16inches wide) were woven, according to the invention, the first withtwo-ply 840 denier nylon yarn with 3% turns per inch Z (twist-on-twist,"each single end having one-half turn Z producer) as the warp yarn andthe second with a similar warp yarn except that the latter had six turnsper inch Z-ply twist. In both cases, the filling yarn was two-ply 840denier nylon yam with 2% turns S- ply twist. For comparison, a similarwebbing was prepared except that, in this instance, the warp yarn wastwo-ply 840 denier nylon (2 /2 turns S-ply twist). This construction istypical of an automotive safety webbing now in use.

The three test webbings mentioned in the preceding paragraph were testedfor surface abrasion resistance by repeated drawing of the same througha conventional automotive safety belt buckle in the manner referred toabove. Abrasion became evident after about cycles on the conventionalwebbing and after 400 cycles the webbing became 05 thick due to abrasionthat it was extremely difficult to pass the same through the buckle. incontrast, the webbing of the invention made with the 3% turns ply twistwarp yarn showed no measurable evidence of abrasion after 400 cycles anddemonstrated much less abrasion even after 1,500 cycles than theconventional webbing did at 400 cycles. The webbing made with the sixturns ply twist warp yarn had even greater abrasion resistance andshowed no significant abrasion even after l0,000 test cycles.

The accompanying drawing is a perspective view of a laptype safety beltwith a conventional form of belt buckle, it

being understood that this is given only for the sake of illustrationsince the invention is equally applicable to shoulder harness ortorso-type belts or other forms of lap belts or safety restraintsystems. As shown, the belt includes the web 2 which carries the buckle4 and the connecting web 6 with the usual means 8 at its end for lockingwith cooperating means on the buckle 4. As will be understood, the beltmay be tightened by pulling on the end of web 2 so that the web slidesover the buckle bar 10 and passes over the edge 12 of the slot 13 in theback of the buckle. The resultant chafing of the web 2 with the bar 10and edge 12 causes some of the objectionable abrasion in conventionalwebbings. Similar chafing and resultant abrasion occur when the belt isloosened for subsequent use. This undesired abrasion, in adjusting thelength of the belt, is obviated with the webbings of the invention.

It will be recognized from the foregoing that various modifications ofthe invention as described above may be made without deviating from thescope thereof. Thus, as indicated, the invention contemplates use of thepresent webbing in any form of safety restraint system, (lap, torso orother type) for use in automobiles or other vehicles, e.g. aircraft,wherein one or more webbings are employed. Thus, one form of safety beltaccording to the invention comprises a woven webbing which carries anadjustable buckle and a second woven webbing having means at one end forlocking engagement with the buckle,

at least the webbing which carries the buckle and preferably bothwebbings comprising, as the warp, plied yarn made up of two ro more endsof singles yarn, the ply twist being in the same direction as the twistin the singles before plying. However, broadly speaking, the safetyrestraint system of the invention will comprise one or more safetywebbings and means for adjusting the webbing for safety restraint wheremanual or automatic adjustment or movement of the webbing tends toinduce abrasion, e.g. restraint systems employing inertia or windupreels, buckles and/or other adjusting means.

lclaim:

1. A safety restraint system including a woven safety webbing whichcomprises, as the warp, plied yarn made up of two or more ends ofsingles yarn of substantially 840 denier nylon, the ply twist being'inthe same direction as the twist in the singles before plying, whereinthe ply twist varies from 2- -l0 turns per inch and the preply twist isin the range of onefourth-three turns per inch, the filling includingplied yarn wherein the ply twist is opposed to the twist in the singlesbefore plying and wherein the number of warp ends is from 220- 300 per 115/16 inches webbing and the number of filling ends is from l420 perinch, a buckle adjustably carried by said webbing and means at one endof said webbing for locking engagement with said buckle, wherein saidwebbing is up to lOO times more abrasive resistant than conventionalsafety restraint webbings.

